Field
The present disclosure relates generally to an information-centric network (ICN). More specifically, the present disclosure relates to a system and method for content routing using link-state information in ICNs.
Related Art
The proliferation of the Internet and e-commerce continues to fuel revolutionary changes in the network industry. Today, a significant number of information exchanges, from online movie viewing to daily news delivery, retail sales, and instant messaging, are conducted online. An increasing number of Internet applications are also becoming mobile. However, the current Internet operates on a largely location-based addressing scheme. The two most ubiquitous protocols, the Internet Protocol (IP) and Ethernet protocol, are both based on end-host addresses. That is, a consumer of content can only receive the content by explicitly requesting the content from an address (e.g., IP address or Ethernet media access control (MAC) address) that is typically associated with a physical object or location. This restrictive addressing scheme is becoming progressively more inadequate for meeting the ever-changing network demands.
Recently, information-centric network (ICN) architectures have been proposed in the industry where content is directly named and addressed. Content-Centric Networking (CCN), an exemplary ICN architecture brings a new approach to content transport. Instead of having network traffic viewed at the application level as end-to-end conversations over which content travels, content is requested or returned based on its unique name, and the network is responsible for routing content from the provider to the consumer. Note that content includes data that can be transported in the communication system, including any form of data such as text, images, video, and/or audio. A consumer and a provider can be a person at a computer or an automated process inside or outside the ICN. A piece of content can refer to the entire content or a respective portion of the content. For example, a newspaper article might be represented by multiple pieces of content embodied as data packets. A piece of content can also be associated with metadata describing or augmenting the piece of content with information such as authentication data, creation date, content owner, etc.
At the core of all ICN architectures are name resolution and routing of content, and several approaches have been proposed. In some ICN architectures, the names of data objects are mapped into addresses by means of directory servers, and then address-based routing is used for content delivery. By contrast, a number of ICN architectures use name-based routing of content, which integrates name resolution and content routing. With name-based routing, some of the routers (producers or caching sites) advertise the existence of local copies of named data objects (NDO) or name prefixes denoting a set of objects with names sharing a common prefix, and routes to them are established; the consumers of content issue content requests that are forwarded along the routes to the routers that issued the NDO or name prefix advertisements.
Among the various ICN architectures, CCN uses distributed routing protocols to establish routes over which content requests are forwarded. In CCN, a content request (called an “Interest”) may be sent over one or multiple paths to a name prefix. Some CCN schemes use existing Internet routing protocol, such as link-state Interior Gateway Protocol (IGP), for intra-domain routing, where routers describe their local connectivity and adjacent resources (content). It has also been proposed to integrate domain-level content prefixes into existing Border Gateway Protocol (BGP) to solve the problem of inter-domain content routing.
Exemplary content routing schemes in ICNs include NLSR (Named-data Link State Routing Protocol) and OSPFN (OSPN for Named-data). In both protocols, routers exchange topology information by flooding two types of link-state advertisements (LSA). LSAs can describe the state of physical links just as it is done in traditional link-state routing protocols. In addition, routers flood LSAs about the prefixes for which they have local copies. It is also possible to use distributed hash tables (DHT) running in overlays over the physical infrastructure to accomplish name-based routing, and in such situations, the routing protocol used in the underlay typically consists of a link-state protocol.
One of the problems facing the existing link-state based routing protocols is that they require each router to receive information, such as LSAs, about all replicas of each published named data object or name prefix advertised in the network, and hence are not scalable.